Measuring weights for a patient on a hospital bed, who cannot move easily, is generally very difficult. There is no good solution which can do this task conveniently and reliably. Here, we have offered a new method and system to do this for beds and other objects, using Z-casters, as explained below. The calibration method is also needed for such a system/method. The invention and embodiments described here, below, have not been addressed or presented, in any prior art.